Preheat the oven to 380F/190C/170c fan/gas 5.

Soak the cashew nuts in water before you start the recipe for at least 3 hours.

Combine together all the topping ingredients and set aside.

Heat the oil in a large frying pan over medium-low heat. Add the onion with a pinch of salt and cover the pan. Cook for 5 minutes or so, to encourage the onion to soften and sweat, then remove the lid and cook for further 5 minutes.

Meanwhile, bring a large pan of water to a boil, add the leek rounds and simmer for about 5 minutes. You can alternatively, steam them. Drain and set aside.

Drain the cashew nuts and put them into a blender. add the hot stock and blitz. Add the soft onions and mustard and blitz again. It should be quite smooth. Season with salt and pepper to taste.

Spread the leeks and a handful of spinach if you like in a shallow oven dish ( about 1.5ml capacity ) or 2 individual small pie dishes.

Pour the cashew cream sauce, then top with the almond and oat topping then put the dish in the oven and bake for about 20 minutes. Serve straight away! And of course - enjoy :)